English Medium Class 10 - CBSE Important Questions for Science

Raisins are wiped off gently before final weighing with the help of

The step(s) necessary for determining the percentage of water absorbed by raisins is/are:

The colour of an aqueous solution of zinc sulphate as observed in the laboratory is:

(1) Green 

(2) Yellow 

(3) Blue 

(4) Colourless

To show that zinc is a more active metal than copper, the correct procedure is to: 

(1) add dilute nitric acid on strips of both the metals. 

(2) observe transmission of heat through strips of zinc and copper. 

(3) prepare solution of zinc sulphate and hang strip of copper into it. 

(4) prepare solution of copper sulphate and hang strip of zinc into it. 

In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?

(i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?
(ii) What type of reaction is this?
(iii) Write a balanced chemical equation to represent the above reaction.

Show the formation of Na2O by the transfer of electrons. 

(a) Design an activity to demonstrate the decomposition reaction of lead nitrate.

(b) Draw labelled diagram of the experimental set-up. List two main observations.

(c) Write balanced chemical equation for the reaction stating the physical state of the reactant and the products.

What is observed after about 1 hour of adding the strips of copper and aluminium separately to the ferrous sulphate solution filled in two beakers? Name the reaction if any change in colour is noticed. Also, write a chemical equation for the reaction.

A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment. 

Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Zinc reacts with silver nitrate to produce zinc nitrate and silver.

Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

What is thermit process? Where is this process used? Write a balanced chemical equation for the reaction involved.

Name the substances that are getting oxidised and reduced in the process.

Write the name and molecular formula of a carbon compound having its name suffixed with "-ol" and having two carbon atoms in its molecule. With the help of a chemical equation indicate what happens when this compound is heated with excess conc. H₂SO₄.

Classify the following reaction into different type:

AgNO₃(aq) + NaCl(aq) →AgCl(s) + NaNO₃(aq)

Classify the following reaction into different type:

\[\ce{2KClO3(s)->[\Delta] 2KCl(aq) + 3O2(g)}\]

Classify the following reaction into different type:

Zn + CuSO₄ → ZnSO₄ + Cu

When a potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed.

What is the colour of this precipitate? Name the compound precipitated.

When a potassium iodide solution is added to a solution of lead (II) nitrate in a test tube, a precipitate is formed.

Write the balanced chemical equation for this reaction.